package zhupf.test.juc;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * ReadWriteLock:读写锁，当高并发多个线程访问一个资源类时，当一个线程进行的写的操作时，不允许其他线程对这个资源类进行操作
 * 不论是读还是写，当一个线程对这个资源类进行读的操作时，允许其他线程进行读的操作
 */
public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCache myCache = new MyCache();
        for(int i = 1;i<=5;i++){
            final int temp = i;
            new Thread(()->{
                myCache.put(temp+"",temp+"");
            },String.valueOf(i)).start();
        }
        for(int i = 1;i<=5;i++){
            final int temp = i;
            new Thread(()->{
                myCache.get(temp+"");
            },String.valueOf(i)).start();
        }
    }
}
class MyCache{
    private volatile Map<String,Object> map = new HashMap<>();

    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    public void put(String key ,Object value){
        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"\t进行写入");
            try {
                TimeUnit.MILLISECONDS.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            map.put(key,value);
            System.out.println(Thread.currentThread().getName()+"\t写入完成");
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.writeLock().unlock();
        }

    }
    public void get(String key){
        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName()+"\t开始读取");
            try {
                TimeUnit.MILLISECONDS.sleep(300);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"\t读取完成=="+map.get(key));
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            readWriteLock.readLock().unlock();
        }

    }
}
